One of the major consequences of expansive urban growth is the degradation and loss of productive agricultural land and agroecosystem functions. Four landscape metrics—Percentage of Land (PLAND), Mean Parcel Size (MPS), Parcel Density (PD), and Modified Simpson’s Diversity Index (MSDI)—were calculated for 1 km × 1 km cells along three 50 km-long transects that extend out from the Adelaide CBD, in order to analyze variations in landscape structures. Each transect has different land uses beyond the built-up area, and they differ in topography, soils, and rates of urban expansion. Our new findings are that zones of agricultural land fragmentation can be identified by the relationships between MPS and PD, that these occur in areas where PD ranges from 7 and 35, and that these occur regardless of distance along the transect, land use, topography, soils, or rates of urban growth. This suggests a geometry of fragmentation that may be consistent, and indicates that quantification of both land use and land-use change in zones of fragmentation is potentially important in planning.
Rice production underpins the national economy and the most rural livelihoods in Cambodia, but it is negatively impacted by repeated droughts. The research reported on in this paper focuses on relationships between drought occurrences in Cambodia’s most drought-prone province (Kampong Speu) and (i) damage to the annual rice harvest between 1994 and 2011, and (ii) the Niño 3.4 index. Droughts were identified using the Standardised Precipitation Index (SPI). In seven of the years between 1994 and 2006 droughts damaged >1000 ha of rice in the Kampong Speu province. Furthermore, in 11 years >200 ha of rice were damaged. A critical success index of 0.66 obtained for an analysis of SPI-defined drought and area rice damage in the province indicates a strong statistical relationship. A statistically significant correlation (r = −0.455) was achieved between Niño 3.4 and 12-month SPI values lagged by three months, this indicates the importance of ENSO linkages in explaining drought in this region. Late season droughts lead to greater rice damage than early- and mid-season droughts.
Land use and land cover were mapped between 3500 and 5000 meters above sea level m.a.s.l. in the Río Chambo basin in south-central Ecuador from Landsat MSS, TM, ETM and OLI imagery acquired between 1979 and 2014. The area mapped has been dominated by páramo and a variety of agricultural land uses since 1979. The main land-use transitions have been from páramo to agriculture, native forest to páramo and agriculture, and agriculture back to páramo. Significant areas of páramo have remained unchanged over the 35-year period analyzed, while the area of native forest has declined and that of bare soil increased. Plantations of non-native timber species increased from 1979 to 1999, but their area has now declined. Most land-use transformations have occurred at lower elevations in the 3500–5000 m.a.s.l. range. This is particularly the case for the loss of native forest and the degradation of páramo and agriculture to areas of bare (eroded) soils. A drivers-based approach revealed that these land-use transformations were related to import substitution and afforestation policies geared toward internal markets, exports and environmental conservation.
Some authorities argue that land is the most fundamental of natural resources. If their arguments fail to convince, we certainly have to cede that land is a limited natural resource. Aside from a few thousand Moken living on the Andaman Sea, humans are tied to the land. Most of us live, eat and sleep on land, even oil rig workers in the Gulf of Mexico, Filipino merchant seamen, Japanese fishermen and British naval ratings divide their lives between sea and land. As the world’s population has grown we have not, with the exception of the industrious Dutch, created land at the expense of the sea. The 29% of the world’s surface that is land, has for many millennia been vitally important in terms of how societies have evolved. Land resources have fed and clothed us, enabled us to build things, and spawned conflicts.
Remnant midwestern oak savannas in the USA have been altered by fire suppression and the encroachment of woody evergreen trees and shrubs. The Gus Engeling Wildlife Management Area (GEWMA) near Palestine, Texas represents a relatively intact southern example of thickening and evergreen encroachment in oak savannas. In this study, 18 images from the CHRIS/PROBA (Compact High-Resolution Imaging Spectrometer/Project for On-Board Autonomy) sensor were acquired between June 2009 and October 2010 and used to explore variation in canopy dynamics among deciduous and evergreen trees and shrubs, and savanna grassland in seasonal leaf-on and leaf-off conditions. Nadir CHRIS images from the 11 useable dates were processed to surface reflectance and a selection of vegetation indices (VIs) sensitive to pigments, photosynthetic efficiency, and canopy water content were calculated. An analysis of temporal VI phenology was undertaken using a fishnet polygon at 90 m resolution incorporating tree densities from a classified aerial photo and soil type polygons. The results showed that the major differences in spectral phenology were associated with deciduous tree density, the density of evergreen trees and shrubs—especially during deciduous leaf-off periods—broad vegetation types, and soil type interactions with elevation. The VIs were sensitive to high densities of evergreens during the leaf-off period and indicative of a photosynthetic advantage over deciduous trees. The largest differences in VI profiles were associated with high and low tree density, and soil types with the lowest and highest available soil water. The study showed how time series of hyperspectral data could be used to monitor the relative abundance and vigor of desirable and less desirable species in conservation lands.